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x - definition and synonyms

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noun [countable/uncountable]     x pronunciation in British English
Word Forms

or X     X pronunciation in British English

  1. 1
    the 24th letter of the English alphabet. X is a consonant.
    Synonyms and related words
  2. 2
    maths used in mathematics for showing a number whose value you do not know

    In this equation, X equals four.

  3. 3


    used instead of saying the name of a person or place when you do not know it, or when you are using them as an example

    Let us say Mr X gives a property to his son...

  4. 4
    informal a symbol used for writing a kiss, usually at the end of a letter
  5. 5
    the Roman numeral for 10
    Synonyms and related words
  6. 6


    used in the past for saying that a film was not suitable for people under the age of 18
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a lifestyle focussing on simple pleasures such as comfort and cosiness in the home, and spending time with friends and family

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a form of location that involves the underwater detonation of a bomb which causes sound waves that are picked up by ships

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